Designers and manufacturers of known automobile brake systems have frequently accomplished brake system operating noise reduction by incorporating various noise reduction elements or materials, often in the nature of an add-on noise insulator or shim device, into the brake system. Such noise reducers often take the form of single or multiple layers of sheet steel, of single or multiple layers of a prepreg material such as filament-reinforced cured thermosetting resin, or rubber-like elastomeric coatings, or combinations of the aforementioned, or of still other materials in an appropriate composition and configuration. Attachment of such noise reducers to the cooperating brake friction pad has typically been accomplished by a variety of mechanical means (e.g., rivets, threaded bolts, bent tabs, etc.), by the use of room-temperature stick-on adhesives, or by the high-temperature curing of thermosetting adhesives. There has been no known attempt to effectively form a noise reducer integral with a disc brake friction pad and backing plate element combination using only a friction pad material to thereby achieve an assembly reduced-noise capability without having to incorporate a separate and additional part into the assembly during manufacture.
U.S. Pat. No. 3,027,979 issued in the name of Pocock discloses a brake structure having friction material molded integrally with a backing plate element but not extruded through the backing plate to form a shim-like noise reducer element.
European Patent Application No. 90116561.3 (Publication No. 0 415 381 A3) assigned to Sumitomo also discloses a brake structure in which the assembly friction material extends into a backing plate member opening but not beyond to form an additional noise reducer element. See also the similar disclosure of Japan Patent Application No. 55-139534 also owned by Sumitomo.
United Kingdom Patent Application No. GB 2 190 968 A granted to Textas GmbH likewise teaches a disc brake friction member wherein the friction material is extruded into but not beyond carrier plate openings and thus forms no noise reducer element at the opposite face of the carrier plate.
France Patent No. 3,322,322 granted to Societe Anonyme Francaise du Ferodo also discloses a method of forming a brake friction member wherein the member friction material is pressed and extruded only into openings in the included brake assembly metallic support element. No attempt is made to thereby create an integral shim-like noise reducer member at the opposite face of the support element.
None of the cited brake system friction member teachings disclose or even suggest that an effective braking noise reduction capability can be advantageously incorporated into a brake system friction member assembly by forming a shim-like noise reducer element from the assembly friction material or from a variant of that material at the time of assembly material molding. In this manner we eliminate any subsequent need to separately form and separately attach a noise reducer or noise isolator element to the assembly to develop the desired noise reduction capability.